Olayinka Olutoye is a MSc. student at the University of Greenwich. Here, she describes her project work within the Microbiology Department of the Hampshire Hospital NHS Foundation Trust, Basingstoke, to investigate the clinical significance of the QuickFISH™ assay:
The QuickFISH assays from AdvanDx use Peptide Nucleic Acid (PNA) Probe technology to rapidly identify bacterial species in positive blood cultures. Using the Staphylococcus QuickFISH kit, we have been able to quickly identify Staphylococcus aureus and coagulase negative Staphylococcus (CoNS) gram-positive cocci in clusters. We have also used the Gram negative QuickFISH kits to distinguish between gram negative bacilli species: Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. All of these specific identifications were achieved in less than 30 minutes following a positive blood culture detection by the BacT/ ALERT® System.
The QuickFISH format is an improved version of the original PNA FISH system developed by AdvanDx. This involved four simple processing stages that took a total of 90 minutes to complete1. The new QuickFISH assay is performed in only three easy stages and takes less than 30 minutes to obtain results. Firstly, sample fixation is performed on the pre-formatted slides, followed by hybridization and finally examination under a fluorescence microscope. QuickFISH eliminates the washing stage, which makes it faster and easier to perform. The test is presented in a convenient kit format which enables samples to be examined either as a batch or on a one-off basis. This prevents wastage but ensures responsiveness to clinical requirements.
The objective of the study was to explore the clinical importance of the QuickFISH assays in antibiotic stewardship. The work has shown that their use can lead to early alteration of the antibiotic therapy as opposed to waiting an additional 48 hours before culture results are obtained. This promotes the use of more targeted antibiotic therapy and prevents overuse of broad spectrum antibiotics. Thus, they may play a role in helping prevent hospital acquired infections such as Clostridium difficile and reducing development of antimicrobial resistance. Targeting therapy sooner can reduce the cost of hospital stays and antibiotics for multidrug-resistant bacteria.
Note: BacT/ALERT is a registered trademark of BioMérieux SA
Note: This article was originally published in Leading Edge: Winter 2014/15. If you’d like to read similar news and articles, please visit: www.alphalabs.co.uk/leading-edge